read_config_file.c

#include "config.h"

#include <string.h>
#include <stdlib.h>
#include <ctype.h>

#include "common.h"

static int line_no;
static char *filename;
static int error_count = 0;

static arg_type_info *parse_type(char **str);

Function *list_of_functions = NULL;

/* Map of strings to type names. These do not need to be in any
 * particular order */
static struct list_of_pt_t {
	char *name;
	enum arg_type pt;
} list_of_pt[] = {
	{
	"void", ARGTYPE_VOID}, {
	"int", ARGTYPE_INT}, {
	"uint", ARGTYPE_UINT}, {
	"long", ARGTYPE_LONG}, {
	"ulong", ARGTYPE_ULONG}, {
	"octal", ARGTYPE_OCTAL}, {
	"char", ARGTYPE_CHAR}, {
	"short", ARGTYPE_SHORT}, {
	"ushort", ARGTYPE_USHORT}, {
	"float", ARGTYPE_FLOAT}, {
	"double", ARGTYPE_DOUBLE}, {
	"addr", ARGTYPE_ADDR}, {
	"file", ARGTYPE_FILE}, {
	"format", ARGTYPE_FORMAT}, {
	"string", ARGTYPE_STRING}, {
	"bytes", ARGTYPE_BYTES}, {
	"array", ARGTYPE_ARRAY}, {
	"struct", ARGTYPE_STRUCT}, {
	"enum", ARGTYPE_ENUM}, {
	NULL, ARGTYPE_UNKNOWN}	/* Must finish with NULL */
};

/* Array of prototype objects for each of the types. The order in this
 * array must exactly match the list of enumerated values in
 * common.h */
static arg_type_info arg_type_prototypes[] = {
	{ ARGTYPE_VOID },
	{ ARGTYPE_INT },
	{ ARGTYPE_UINT },
	{ ARGTYPE_LONG },
	{ ARGTYPE_ULONG },
	{ ARGTYPE_OCTAL },
	{ ARGTYPE_CHAR },
	{ ARGTYPE_SHORT },
	{ ARGTYPE_USHORT },
	{ ARGTYPE_FLOAT },
	{ ARGTYPE_DOUBLE },
	{ ARGTYPE_ADDR },
	{ ARGTYPE_FILE },
	{ ARGTYPE_FORMAT },
	{ ARGTYPE_STRING },
	{ ARGTYPE_STRING_N },
	{ ARGTYPE_BYTES },
	{ ARGTYPE_BYTES_N },
	{ ARGTYPE_ARRAY },
	{ ARGTYPE_ENUM },
	{ ARGTYPE_STRUCT },
	{ ARGTYPE_POINTER },
	{ ARGTYPE_UNKNOWN }
};

arg_type_info *
lookup_prototype(enum arg_type at) {
	if (at >= 0 && at <= ARGTYPE_COUNT)
		return &arg_type_prototypes[at];
	else
		return &arg_type_prototypes[ARGTYPE_COUNT]; /* UNKNOWN */
}

static arg_type_info *
str2type(char **str) {
	struct list_of_pt_t *tmp = &list_of_pt[0];

	while (tmp->name) {
		if (!strncmp(*str, tmp->name, strlen(tmp->name))
				&& index(" ,()#*;012345[", *(*str + strlen(tmp->name)))) {
			*str += strlen(tmp->name);
			return lookup_prototype(tmp->pt);
		}
		tmp++;
	}
	return lookup_prototype(ARGTYPE_UNKNOWN);
}

static void
eat_spaces(char **str) {
	while (**str == ' ') {
		(*str)++;
	}
}

static char *
xstrndup(char *str, size_t len) {
	char *ret = (char *) malloc(len + 1);
	strncpy(ret, str, len);
	ret[len] = 0;
	return ret;
}

static char *
parse_ident(char **str) {
	char *ident = *str;

	if (!isalnum(**str) && **str != '_') {
		output_line(0, "Syntax error in `%s', line %d: Bad identifier",
				filename, line_no);
		error_count++;
		return NULL;
	}

	while (**str && (isalnum(**str) || **str == '_')) {
		++(*str);
	}

	return xstrndup(ident, *str - ident);
}

/*
  Returns position in string at the left parenthesis which starts the
  function's argument signature. Returns NULL on error.
*/
static char *
start_of_arg_sig(char *str) {
	char *pos;
	int stacked = 0;

	if (!strlen(str))
		return NULL;

	pos = &str[strlen(str)];
	do {
		pos--;
		if (pos < str)
			return NULL;
		while ((pos > str) && (*pos != ')') && (*pos != '('))
			pos--;

		if (*pos == ')')
			stacked++;
		else if (*pos == '(')
			stacked--;
		else
			return NULL;

	} while (stacked > 0);

	return (stacked == 0) ? pos : NULL;
}

static int
parse_int(char **str) {
	char *end;
	long n = strtol(*str, &end, 0);
	if (end == *str) {
		output_line(0, "Syntax error in `%s', line %d: Bad number (%s)",
				filename, line_no, *str);
		error_count++;
		return 0;
	}

	*str = end;
	return n;
}

/*
 * Input:
 *  argN   : The value of argument #N, counting from 1 (arg0 = retval)
 *  eltN   : The value of element #N of the containing structure
 *  retval : The return value
 *  0      : Error
 *  N      : The numeric value N, if N > 0
 *
 * Output:
 * > 0   actual numeric value
 * = 0   return value
 * < 0   (arg -n), counting from one
 */
static int
parse_argnum(char **str) {
	int multiplier = 1;
	int n = 0;

	if (strncmp(*str, "arg", 3) == 0) {
		(*str) += 3;
		multiplier = -1;
	} else if (strncmp(*str, "elt", 3) == 0) {
		(*str) += 3;
		multiplier = -1;
	} else if (strncmp(*str, "retval", 6) == 0) {
		(*str) += 6;
		return 0;
	}

	n = parse_int(str);

	return n * multiplier;
}

struct typedef_node_t {
	char *name;
	arg_type_info *info;
	struct typedef_node_t *next;
} *typedefs = NULL;

static arg_type_info *
lookup_typedef(char **str) {
	struct typedef_node_t *node;
	char *end = *str;
	while (*end && (isalnum(*end) || *end == '_'))
		++end;
	if (end == *str)
		return NULL;

	for (node = typedefs; node != NULL; node = node->next) {
		if (strncmp(*str, node->name, end - *str) == 0) {
			(*str) += strlen(node->name);
			return node->info;
		}
	}

	return NULL;
}

static void
parse_typedef(char **str) {
	char *name;
	arg_type_info *info;
	struct typedef_node_t *binding;

	(*str) += strlen("typedef");
	eat_spaces(str);

	// Grab out the name of the type
	name = parse_ident(str);

	// Skip = sign
	eat_spaces(str);
	if (**str != '=') {
		output_line(0,
				"Syntax error in `%s', line %d: expected '=', got '%c'",
				filename, line_no, **str);
		error_count++;
		return;
	}
	(*str)++;
	eat_spaces(str);

	// Parse the type
	info = parse_type(str);

	// Insert onto beginning of linked list
	binding = malloc(sizeof(*binding));
	binding->name = name;
	binding->info = info;
	binding->next = typedefs;
	typedefs = binding;
}

static size_t
arg_sizeof(arg_type_info * arg) {
	if (arg->type == ARGTYPE_CHAR) {
		return sizeof(char);
	} else if (arg->type == ARGTYPE_SHORT || arg->type == ARGTYPE_USHORT) {
		return sizeof(short);
	} else if (arg->type == ARGTYPE_FLOAT) {
		return sizeof(float);
	} else if (arg->type == ARGTYPE_DOUBLE) {
		return sizeof(double);
	} else if (arg->type == ARGTYPE_ENUM) {
		return sizeof(int);
	} else if (arg->type == ARGTYPE_STRUCT) {
		return arg->u.struct_info.size;
	} else if (arg->type == ARGTYPE_POINTER) {
		return sizeof(void*);
	} else if (arg->type == ARGTYPE_ARRAY) {
		if (arg->u.array_info.len_spec > 0)
			return arg->u.array_info.len_spec * arg->u.array_info.elt_size;
		else
			return sizeof(void *);
	} else {
		return sizeof(int);
	}
}

#undef alignof
#define alignof(field,st) ((size_t) ((char*) &st.field - (char*) &st))
static size_t
arg_align(arg_type_info * arg) {
	struct { char c; char C; } cC;
	struct { char c; short s; } cs;
	struct { char c; int i; } ci;
	struct { char c; long l; } cl;
	struct { char c; void* p; } cp;
	struct { char c; float f; } cf;
	struct { char c; double d; } cd;

	static size_t char_alignment = alignof(C, cC);
	static size_t short_alignment = alignof(s, cs);
	static size_t int_alignment = alignof(i, ci);
	static size_t long_alignment = alignof(l, cl);
	static size_t ptr_alignment = alignof(p, cp);
	static size_t float_alignment = alignof(f, cf);
	static size_t double_alignment = alignof(d, cd);

	switch (arg->type) {
		case ARGTYPE_LONG:
		case ARGTYPE_ULONG:
			return long_alignment;
		case ARGTYPE_CHAR:
			return char_alignment;
		case ARGTYPE_SHORT:
		case ARGTYPE_USHORT:
			return short_alignment;
		case ARGTYPE_FLOAT:
			return float_alignment;
		case ARGTYPE_DOUBLE:
			return double_alignment;
		case ARGTYPE_ADDR:
		case ARGTYPE_FILE:
		case ARGTYPE_FORMAT:
		case ARGTYPE_STRING:
		case ARGTYPE_STRING_N:
		case ARGTYPE_BYTES:
		case ARGTYPE_BYTES_N:
		case ARGTYPE_POINTER:
			return ptr_alignment;

		case ARGTYPE_ARRAY:
			return arg_align(&arg->u.array_info.elt_type[0]);

		case ARGTYPE_STRUCT:
			return arg_align(arg->u.struct_info.fields[0]);

		default:
			return int_alignment;
	}
}

static size_t
align_skip(size_t alignment, size_t offset) {
	if (offset % alignment)
		return alignment - (offset % alignment);
	else
		return 0;
}

/* I'm sure this isn't completely correct, but just try to get most of
 * them right for now. */
static void
align_struct(arg_type_info* info) {
	size_t offset;
	int i;

	if (info->u.struct_info.size != 0)
		return;			// Already done

	// Compute internal padding due to alignment constraints for
	// various types.
	offset = 0;
	for (i = 0; info->u.struct_info.fields[i] != NULL; i++) {
		arg_type_info *field = info->u.struct_info.fields[i];
		offset += align_skip(arg_align(field), offset);
		info->u.struct_info.offset[i] = offset;
		offset += arg_sizeof(field);
	}

	info->u.struct_info.size = offset;
}

static arg_type_info *
parse_nonpointer_type(char **str) {
	arg_type_info *simple;
	arg_type_info *info;

	if (strncmp(*str, "typedef", 7) == 0) {
		parse_typedef(str);
		return lookup_prototype(ARGTYPE_UNKNOWN);
	}

	simple = str2type(str);
	if (simple->type == ARGTYPE_UNKNOWN) {
		info = lookup_typedef(str);
		if (info)
			return info;
		else
			return simple;		// UNKNOWN
	}

	info = malloc(sizeof(*info));
	info->type = simple->type;

	/* Code to parse parameterized types will go into the following
	   switch statement. */

	switch (info->type) {

	/* Syntax: array ( type, N|argN ) */
	case ARGTYPE_ARRAY:
		(*str)++;		// Get past open paren
		eat_spaces(str);
		if ((info->u.array_info.elt_type = parse_type(str)) == NULL)
			return NULL;
		info->u.array_info.elt_size =
			arg_sizeof(info->u.array_info.elt_type);
		(*str)++;		// Get past comma
		eat_spaces(str);
		info->u.array_info.len_spec = parse_argnum(str);
		(*str)++;		// Get past close paren
		return info;

	/* Syntax: enum ( keyname=value,keyname=value,... ) */
	case ARGTYPE_ENUM:{
		struct enum_opt {
			char *key;
			int value;
			struct enum_opt *next;
		};
		struct enum_opt *list = NULL;
		struct enum_opt *p;
		int entries = 0;
		int ii;

		eat_spaces(str);
		(*str)++;		// Get past open paren
		eat_spaces(str);

		while (**str && **str != ')') {
			p = (struct enum_opt *) malloc(sizeof(*p));
			eat_spaces(str);
			p->key = parse_ident(str);
			if (error_count) {
				free(p);
				return NULL;
			}
			eat_spaces(str);
			if (**str != '=') {
				free(p->key);
				free(p);
				output_line(0,
						"Syntax error in `%s', line %d: expected '=', got '%c'",
						filename, line_no, **str);
				error_count++;
				return NULL;
			}
			++(*str);
			eat_spaces(str);
			p->value = parse_int(str);
			p->next = list;
			list = p;
			++entries;

			// Skip comma
			eat_spaces(str);
			if (**str == ',') {
				(*str)++;
				eat_spaces(str);
			}
		}

		info->u.enum_info.entries = entries;
		info->u.enum_info.keys =
			(char **) malloc(entries * sizeof(char *));
		info->u.enum_info.values =
			(int *) malloc(entries * sizeof(int));
		for (ii = 0, p = NULL; list; ++ii, list = list->next) {
			if (p)
				free(p);
			info->u.enum_info.keys[ii] = list->key;
			info->u.enum_info.values[ii] = list->value;
			p = list;
		}
		if (p)
			free(p);

		return info;
	}

	case ARGTYPE_BYTES:
	case ARGTYPE_STRING:
		if (!isdigit(**str) && **str != '[') {
			/* Oops, was just a simple string after all */
			free(info);
			return simple;
		}

		info->type = (info->type == ARGTYPE_STRING) ? ARGTYPE_STRING_N : ARGTYPE_BYTES_N;

		/* Backwards compatibility for string0, string1, ... */
		if (isdigit(**str)) {
			info->u.string_n_info.size_spec = -parse_int(str);
			return info;
		}

		(*str)++;		// Skip past opening [
		eat_spaces(str);
		info->u.string_n_info.size_spec = parse_argnum(str);
		eat_spaces(str);
		(*str)++;		// Skip past closing ]
		return info;

	// Syntax: struct ( type,type,type,... )
	case ARGTYPE_STRUCT:{
		int field_num = 0;
		(*str)++;		// Get past open paren
		info->u.struct_info.fields =
			malloc((MAX_ARGS + 1) * sizeof(void *));
		info->u.struct_info.offset =
			malloc((MAX_ARGS + 1) * sizeof(size_t));
		info->u.struct_info.size = 0;
		eat_spaces(str); // Empty arg list with whitespace inside
		while (**str && **str != ')') {
			if (field_num == MAX_ARGS) {
				output_line(0,
						"Error in `%s', line %d: Too many structure elements",
						filename, line_no);
				error_count++;
				return NULL;
			}
			eat_spaces(str);
			if (field_num != 0) {
				(*str)++;	// Get past comma
				eat_spaces(str);
			}
			if ((info->u.struct_info.fields[field_num++] =
						parse_type(str)) == NULL)
				return NULL;

			// Must trim trailing spaces so the check for
			// the closing paren is simple
			eat_spaces(str);
		}
		(*str)++;		// Get past closing paren
		info->u.struct_info.fields[field_num] = NULL;
		align_struct(info);
		return info;
	}

	default:
		if (info->type == ARGTYPE_UNKNOWN) {
			output_line(0, "Syntax error in `%s', line %d: "
					"Unknown type encountered",
					filename, line_no);
			free(info);
			error_count++;
			return NULL;
		} else {
			return info;
		}
	}
}

static arg_type_info *
parse_type(char **str) {
	arg_type_info *info = parse_nonpointer_type(str);
	while (**str == '*') {
		arg_type_info *outer = malloc(sizeof(*info));
		outer->type = ARGTYPE_POINTER;
		outer->u.ptr_info.info = info;
		(*str)++;
		info = outer;
	}
	return info;
}

static Function *
process_line(char *buf) {
	Function fun;
	Function *fun_p;
	char *str = buf;
	char *tmp;
	int i;
	int float_num = 0;

	line_no++;
	debug(3, "Reading line %d of `%s'", line_no, filename);
	eat_spaces(&str);
	fun.return_info = parse_type(&str);
	if (fun.return_info == NULL)
		return NULL;
	if (fun.return_info->type == ARGTYPE_UNKNOWN) {
		debug(3, " Skipping line %d", line_no);
		return NULL;
	}
	debug(4, " return_type = %d", fun.return_info->type);
	eat_spaces(&str);
	tmp = start_of_arg_sig(str);
	if (!tmp) {
		output_line(0, "Syntax error in `%s', line %d", filename,
				line_no);
		error_count++;
		return NULL;
	}
	*tmp = '\0';
	fun.name = strdup(str);
	str = tmp + 1;
	debug(3, " name = %s", fun.name);
	fun.params_right = 0;
	for (i = 0; i < MAX_ARGS; i++) {
		eat_spaces(&str);
		if (*str == ')') {
			break;
		}
		if (str[0] == '+') {
			fun.params_right++;
			str++;
		} else if (fun.params_right) {
			fun.params_right++;
		}
		fun.arg_info[i] = parse_type(&str);
		if (fun.arg_info[i] == NULL) {
			output_line(0, "Syntax error in `%s', line %d"
					": unknown argument type",
					filename, line_no);
			error_count++;
			return NULL;
		}
		if (fun.arg_info[i]->type == ARGTYPE_FLOAT)
			fun.arg_info[i]->u.float_info.float_index = float_num++;
		else if (fun.arg_info[i]->type == ARGTYPE_DOUBLE)
			fun.arg_info[i]->u.double_info.float_index = float_num++;
		eat_spaces(&str);
		if (*str == ',') {
			str++;
			continue;
		} else if (*str == ')') {
			continue;
		} else {
			if (str[strlen(str) - 1] == '\n')
				str[strlen(str) - 1] = '\0';
			output_line(0, "Syntax error in `%s', line %d at ...\"%s\"",
					filename, line_no, str);
			error_count++;
			return NULL;
		}
	}
	fun.num_params = i;
	fun_p = malloc(sizeof(Function));
	if (!fun_p) {
		perror("ltrace: malloc");
		exit(1);
	}
	memcpy(fun_p, &fun, sizeof(Function));
	return fun_p;
}

void
read_config_file(char *file) {
	FILE *stream;
	char buf[1024];

	filename = file;
	stream = fopen(filename, "r");
	if (!stream) {
		return;
	}

	debug(1, "Reading config file `%s'...", filename);

	line_no = 0;
	while (fgets(buf, 1024, stream)) {
		Function *tmp;

		error_count = 0;
		tmp = process_line(buf);

		if (tmp) {
			debug(2, "New function: `%s'", tmp->name);
			tmp->next = list_of_functions;
			list_of_functions = tmp;
		}
	}
	fclose(stream);
}